Even if you remove all availability from the calendar(s) related to a listing -- and have Propose Showtimes enabled -- prospects may still see and be able to select pre-approved showtimes.
This will occur when a calendar associated with the listing is configured to allow more than one showing at a given showtime and when one of the two events has occurred:
- A showtime for the listing has been proposed by a prospect and accepted by you (or someone on your team).
- You or someone on your team has added a custom showtime for the listing.
Basically, any upcoming showing for that listing will be displayed as a pre-approved showtime when there are more showings allowed on that same showtime.